From somata of the pacemaker neurons in the Squilla heart ganglion, pacemaker potentials for the spontaneous periodic burst discharge are recorded with intracellular electrodes. The electrical activity is composed of slow potentials and superimposed spikes, and is divided into four types, which are: (a) "mammalian heart" type, (b) "slow generator" type, (c) "slow grower" type, and (d) "slow def...

The mantis shrimp Squilla mantis shows a graded series of avoidance/escape responses to visual and mechanical (vibration and touch) rostral stimuli. A low-threshold response is mediated by the simultaneous protraction of the thoracic walking legs and abdominal swimmerets and telson, producing a backwards 'lurch' or jump that can displace the animal by up to one-third of its body length, but lea...

The pacemaker neurons of the heart ganglion are innervated from the CNS through two pairs of acceleratory nerves. The effect of acceleratory nerve stimulation was examined with intracellular electrodes from the pacemaker cells. The major effects on the pacemaker potential were an increase in the rate of rise of the spontaneous depolarization and in the duration of the plateau. The aftereffect o...

As part of a broad, multldlsciplinary effort to monitor the impact of petroleum exploration activities on the outer continental shelf areas of the Gulf of Mexico, the local effects of a drilllng rig on the benthic environment have been investigated. Petroleum hydrocarbons in or on seawater can become associated with suspended sediment partlcles I and be transported downward and incorporated int...

Many crustaceans detect odors from distant sources (such as conspecifics or prey items) by using chemosensory sensillae (aesthetascs) on their antennules. The morphology and arrangement of the aesthetascs on the antennule and the movement of the antennule through the surrounding fluid during olfactory sampling affect the flow of odorants around the sensillae and thus odorant access to receptors...

> Abstract The mantis shrimps (Stomatopoda) are quintessential marine predators. The combination of powerful raptorial appendages and remarkably developed sensory systems place the stomatopods among the most effi cient invertebrate predators. High level phylogenetic analyses have been so far based on morphology. Crown-group Unipeltata appear to have diverged in two broad directions from the out...

Optical microscopy, electron microscopy and microspectrophotometry were used to characterize pigments in the eyes of planktonic larvae of two species of the lysiosquilloid stomatopod Pullosquilla, P. litoralis and P. thomassini, which live sympatrically in French Polynesia. In contrast to the adult retina, which contains a diverse assortment of visual pigments in the main rhabdoms, the principa...

Gonodactyloid stomatopod crustaceans possess polarization vision, which enables them to discriminate light of different e-vector angle. Their unusual apposition compound eyes are divided by an equatorial band of six rows of enlarged, structurally modified ommatidia, the mid-band (MB). The rhabdoms of the two most ventral MB rows 5 and 6 are structurally designed for polarization vision. Here we...

Stomatopods have an extraordinary visual system, incorporating independent movement of their eyes in all three degrees of rotational freedom. In this work, we demonstrate that in the peacock mantis shrimp, Odontodactylus scyllarus, the level of ocular independence is task dependent. During gaze stabilization in the context of optokinesis, there is weak but significant correlation between the le...

The heart of Squilla oratoria contains a cardiac ganglion that consists of 15 intrinsic neurons, supplied by a pair of inhibitory nerves and two pairs of excitatory nerves, arising from the central nervous system. These comprise the extrinsic cardiac innervation. The paired cardio-inhibitor (CI) nerves run out in the 10th pair of nerve roots emerging from the subesophageal ganglion (SEG). The c...